Intrusion detecting apparatus

ABSTRACT

The invention comprises of improvements in motion detecting apparatus, wherein, there is a lens for producing an image of a space under surveilence upon a retina of at least three sensory units spaced from each other in the focal surface of the lens. Each sensory unit comprises of two photoconductive cells, the cells having response characteristics in different but partially overlapping portions of the range of variations of illumination level. The cells are connected in series with a current limiting resistor and a first source of voltage. An output circuit from the sensory units is connected across the circuit including one of the cells and the current limiting resistor. Also included is a source of higher voltage connected through a fixed resistor in series with one cell and the current limiting resistor. The sensor units provide for automatic adaptation of the apparatus to changing levels of illumination of the imaged space. The invention further includes signal processing means for segregating the desired signals from other signals on the basis of their frequencies, a means for producing pulses of uniform energy content in response to signals, a capacitor for receiving the uniform energy pulses and producing a triggering voltage, and a triggering means having a predetermined threshold voltage for turning on the alarm. The invention still further includes a latching means for continuing the operation of the alarm once it is initiated, a reset means for automatically unlatching the apparatus at a predetermined time after the latching, a refresh means for increasing the time of latching in response to continued motion, and means for anticipating motion for a predtermined time interval after the reset operation, which if it occurs, will render the apparatus immediately responsive. The invention further includes means for delaying the arming of the apparatus and for indicating when the arming is being processed.

United States Patent [191 Campman 1 1 INTRUSION DETECTING APPARATUS [75] Inventor: James P. Campman, Silver Spring,

[73] Assigneez Vidar Laboratories, Inc.,

Kensington, Md. [22] Filed: Jan. 15, 1973 [21] Appl. No.: 323,751

Related US. Application Data [63] Continuation-impart of Ser. No. 248,211, April 27,

1972, Pat. No. 3,781,842.

[52] US. Cl 340/258 B, 250/221, 340/228 S, 340/420 [51] Int. Cl. G08b 19/00, G08b 13/18 [58] Field of Search 340/258 B, 258 A, 228 S, 340/227 R, 276, 420; 250/210 X, 210, 209 X, 209, 221 X, 221, 222 R, 211 X [56] References Cited UNITED STATES PATENTS 2.004.253 6/1935 Tasker 250/211 R 3,089,065 5/1963 Worden 340/258 B 3,122,638 2/1964 Steele et a1. 250/211 R 3,631,434 12/1971 Schwartz 340/228 S 3,680,073 7/1972 Humphrey et a1. 340/258 A 3,706,961 12/1972 Sugiura 340/258 A 3,745,550 7/1973 Anthony et al. 1. 340/258 B 3,781,842 12/1973 Campman 340/258 B Primary ExaminerGlen R. Swann, Ill Attorney, Agent, or Firm-Jack H. Linscott [57] ABSTRACT The invention comprises of improvements in motion detecting apparatus, wherein, there is a lens for pro- 3,840,86 Oct. 8, 1974 tially overlapping portions of the range of variations of.

illumination level. The cells are connected in series with a current limiting resistor and a first source of voltage. An output circuit from the sensory units is connected across the circuit including one of the cells and the current limiting resistor. Also included is a source of higher voltage connected through a fixed resistor in series with one cell and the current limiting resistor. The sensor units provide for automatic adaptation of the apparatus to changing levels of illumination of the imaged space. The invention further includes signal processing means for segregating the desired signals from other signals on the basis of their frequencies, a means for producing pulses of uniform energy content in response to signals, a capacitor for receiving the uniform energy pulses and producing a triggering voltage, and a triggering means having a predetermined threshold voltage for turning on the alarm. The invention still further includes a latching means for continuing the operation of the alarm once it is initiated, a reset means for automatically unlatching the apparatus at a predetermined time after the latching, a refresh means for increasing the time of latching in response to continued motion, and means for anticipating motion for a predtermined time interval after the reset operation, which if it occurs, will render the apparatus immediately responsive. The invention further includes means for delaying the arming of the apparatus and for indicating when the arming is being processed.

10 Claims, 11 Drawing Figures DELAY .ARMING AND MEMORY CLEARANCE INSTANT LATCH PREAMPLIFIER. 4a FILQI'NEIR 1 sensor: SWITCH GATE ALARM l IMPEDANCE l\ H 37 CONVERTOR PULSE PULSECOUNT 44 UNITIZER "EMMY AND ACCEPTANCE g g GATE ' to 5e ANTVICIPATE FUNCTION ,39

namesa- RESET INHIBIT GATE PATENIEU BET 1 74 SHEEISUF 5 l l L FIG.8

INTRUSION DETECTING APPARATUS RELATED APPLICATIONS This application is an improvement upon and a continuation in part of my copending application Ser. No. 248,211, filed Apr. 27, 1972, entitled, Cats Eye Intrusion Detecting Apparatus now U.S. Pat. No. 3,781,842. 1

GENERAL DESCRIPTION OF INVENTION This invention relates to an apparatus designed to view a space or area removed therefrom, to detect any motion that takes place in said space or area and to produce an alarm or indication in response to the motion.

In my prior application a spherical lens means had a retina of photosensitive cells attached to its surface.

-The cells all had the same response characteristics. The

lens produced a pattern of shadows upon the retina, which, when motion took place would cause a change in the pattern of shadows. To obtain optimum signal strength when operating at opposite ends of the range of light levels requires light sensitive cells in the sensory means which-have the light response characteristics most favorable at the operating level. Thus, either the sensory means must be designed to meet the requirements of one level of illumination orthe other, or, two sensory means need to be provided within a given piece of apparatus, with switch means to selectively connect the cells as the light level changed.

A new approach to the problem of response has been taken in the present invention. It is to provide an adaptive function in the sensory means, that is, to provide a sensory means that automatically adapts itself to the operating level of illumination, to produce signals of the optimum strength through out the whole range of changes of illumination from full sun-light to substantially complete darkness. It is an electronic synthesis of a bio-function, for example, that of the human eye which has adaptive characteristics in response to intensity and spectral changes in illumination.

The improvements herein pertain specifically, though not exclusively, to the design and arrangement of components in a sensory means and in the combination of the sensory means with a signal processing apparatus that is tailored to make use of the improvements in the sensory means. The improvements also include built-in apparatus that enables the detector to be readily adapted to the general requirements imposed by the environments in which the apparatus is to .be used, thus increasing the universality of utilization of the apparatus.

OBJECTS OF THE INVENTIONS In the present invention it is an object to provide a detector apparatus having a more uniform response characteristic fo the full range of possible changes .of illumination and to increase the range of response of the apparatus.

It is another object :to ,provide a detector apparatus that is capable of beingiadjusted for different depths .of field of view.

Another objecttofthe inventionis torprovide a detector apparatus which willhave a response-inztheznear infrared region of the lightspectrum,;Particularly,during low levels of visible illumination.

A further object of the invention is to provide within the detector apparatus a control means forselectively altering the response to suit the enviromental conditions. 1

A further object is to provide apparatus wherein the character of the indicating alarm can be selectively changed.

A still further object is to provide a detector apparatus which will be economically within the reach of the average home owner and small business man.

Other objects of the invention will become obvious from the disclosure as it proceeds.

DESCRIPTION OF DRAWINGS In the drawings:

FIG. 1 is a chart disclosing a comparison of the response characteristics of two types of photocells with changes in the levels of illumination;

FIG. 2 is a chart disclosing a comparison of the re spouses of two types of photocells with changes in the spectral content of the illumination;

FIGS. 3A and 3B are similar circuits for two types of cells for the disclosure of the problems in obtaining optimum responses;

FIG. 4 is a schematic view of a sensory unit in which cells having different response characteristics are combined to provide for an automatic adaptation to changes in illumination level;

FIGS. 5A and 5B are schematic views, which together illustrate the electronic circuit of the apparatus;

FIG. 6 is a block diagram of the apparatus for illustrating the important functions of the apparatus;

FIG. 7 is an elevational view of the sensory means partly in section, illustrating the mechanical features of the structure for mounting the lens and the retina;

FIG. 8 is a plan view, partly in section of the sensory means, taken on line'A-A in FIG. 7 looking in the direction of the arrows; and

FIG. 9 is a chart illustrating conditions resulting from two depths of view for illustrating how the orientation and spacing of the sensory units can be used to predetermined the frequency of the real signals.

SPECIFIC DESCRIPTION OF THE INVENTION The photosensitive elements in the present invention are of the photoconductive type. They are composed of a serpentine deposit of a photoconductive material on a'substrate of insulating material. The resistance of the serpentine deposit changes with the intensity of the light which .impinges'upon it and with the length of the deposit that is illuminated. The resistance decreases with increase in light level and with increase of length of the serpentine deposit that is illuminated and vice versa.

Two kinds of photoconductive materials are used in the invention. One is acadmiumsulphide material having adark -(2 ft. candles) resistance in the neighborhoodof 1 to 1.0 megohms and a resistance in the neighborhood of 1,000.0hms at 1,000ft. candles of illumination. The other material is cadmium selenide having a dark (2 ft. candles) resistanceof about 1,000 ohms and aresistance of about 1 ohm at 1,000 ft, candles of i1- lumination. :In .FIG. 1 .curve f represents the resistance changeswithchanges of illumination in the cadmium sulphide .cell ,and curve g represents the resistance changes with changes of illumination on the cadmium selenide cell.

On the same chart. FIG. I, the curves h and i rcspe'ctively represent the variations in the percentage of efficiency with changes of illumination of the cadmium selenide and cadmium sulphide cells. It is important to note the relative values of dark resistance of the two materials to understand the operation of the sensory means.

Another characteristic, not illustrated, which is beneficial, though not of major importance, is the relative temperature response of the materials. The temperature coefficients are a function of the light level as well as of the material. Cadmium sulphide cells have a lower coefficient of resistance and in general its resistance changes inversely with temperature change.

Cadmium selenide has a considerably greater coefficient of resistance and its resistance varies directly with the changes in temperature. The coefficients being also a function of change in light, vary inversely as the light level varies. Thus, in the midregion of illumination level, the'resistance variations due to temperature variations would tend to cancel when the two cells are connected in series, or at least the changes inresistance would be minimized.

The spectral response of the cadmium sulphide and cadmium selenide materials is shown in FIG. 2'of the drawings. As represented, cadmium sulphide k has a usable response that extends over the green portion of the visible light spectrum (5,500 to 5,000 Angstroms), whereas, cadmium selenide j has a usableresponse that extends down into the near infra-red region (7,000 to 7,100 Angstroms). During periods of low illumination a response in the near infra-red region will enhance the response of the sensory units to visible light, and extend the response range of the apparatus to beyond the visible light levels.

When these cells are used for the detection of motion the cells are exposed to two different rates of change of light variations. One is relatively slow, in the matter of hours, that illuminates the field of view and the whole retina. This change in illumination, I term static illumination because the change is so slow that it does not generate a signal. It does, however, cause changes in the response of the sensory means and in that way affects the signal strength. In the case of cadmium sulphide, when the illumination varies from darkness to bright sunlight the resistance of the cell changes from persons move across the sensitive surfaces of the cell to set up pulsating changes in the resistance of the cells. The pulsating changes in the resistances of the cells produce pulsating currents which in passing through a resistance produce pulsating voltage drops across the sensory units. I designate the pulsating change in resistance as partial r or as 8 r, to distinguish from the long term change in resistance of the cells. The signal voltages that are produced is the result of the partial change in resistance 6 r and it is superimposed upon the steady voltage drop that exists because of the level of the illumination being experienced by thecells.

The signal voltage is represented by the following equation:

the current I is assumed to be constant. 7

In FIG. 3A and 3B is a series circuit, each including a fixed resistor R, and a photoconduetor whose resistance-is variable with changing light levels. The two circuits are the same except that in FIG. 3A the photoconductor 3 is one kind of material and in FIG. 3B the photoconductor 4 is of another kind of material, as for example respectiwely cadmium sulphide and 55:11am selenide. In each of the circuits the output is taken from across the photoconduetor. It could, if desired be taken from across the fixed resistor. The only difference would be in the direction of the change of voltage drop obtained. The supply voltage across the circuits is assumed tobe constant. When there is a change in the re sistance of the photoconductive cells there is a change in current in the circuit because the total resistance is changed. The total voltage drop across the circuit is constant'because the supply voltage is constant, thus what happens is merely a redistribution of the voltage drops. The voltage drop across the circuit will be equal to E IR',+ IR where I is the current at any level of illumination, R; 10,000 ohms, R is the resistance of the photoconductive cells at the prevailing light levels and E 1 volt.

From the equation 2,, I 8r/AR it can be seen that the strength of the signal is dependent upon the static resistance AR, which changes with each change in illumination level of the cell. It is necessary to see how changes in AR affects the strength of the output signals in the two circuits.

To exemplify this, there will be three assumed light levels under which cells 3 and 4 will be operating. Since the cells have different resistance characteristics, the resistance for each given light level will be different for each of the cells, and can be determined from the chart in FIG. 1. Let the assumed light levels be 3, 50 and 1,000 foot candles. The following table will show the respective resistances of the cell for each light level.

In the series circuit the only variable is the resistance of the photocells. From table 1 it will be seen that the photocell 3 has a higher resistance at the lower levels of illumination than photocell 4, the ratio is approximately /1 and'at higher levels of illumination the photocell 3 has a higher resistance than cell 4 by a ratio of 10/ 1. Thus, at higher light levels, photocell 3 would require very much smaller current values to obtain a measurable signal voltage than would be required in cell 4 because of its much lower resistance. At the lower light levels, the resistance of cell 3 rises to extremely high values. It would thus require a very high voltage to obtain a current value adequate to produce a measurable signal voltage Referring to FIG. 4 there is a schematic of a circuit in which the cells 3 and 4'are combined to form a single sensory unit. The cells are respectively cadmium sulphide and cadmium selenide cells. They are connected in series with a current limiting resistor 5 having a resistance of 330 ohms. The series circuit is connected across a three volt sourc of energy. A nine volt souce of energy is connected in series with a high resistance resistor, across the photocell 4 and the current limiting 5 resistor 5. The high resistance resistor 6 has a resistance of 1 megohm. The output circuit is connected across the photocell 4 and the currentlimiting resistor 5.

Under very high levels of illumination, the imped-' 10 ance of the cadmium selenide cell 4 is very low. A very high current would be required for it to develope a measurable voltage drop. The cadmium sulphide cell 3 exhibits considerably more impedance at the higher levels of illumination, thus a small current would be required to produce a measurable voltage drop at the output. It is during periods of high illumination levels that the cadmium sulphide cells 3 function to produce the greater voltage drop in the output circuit. On the other hand, at low levels of illumination the resistance of the cadmium sulphide cell 3 becomes so high that no measurable current flows from the 3 volt source through it. At the same time, that the cadmium sulphide cell is experiencing high resistance, the cadmium selenide cell has a much lower resistance and current through it from the nine volt source to produce a measurable voltage drop.

The operation is such that during the highlevels of illumination the cadmium sulphide cell 3 is dominant in producing the signal voltages. During the middle region of illumination levels both of the cells function to produce the voltage drop at the output. During extremely low levels of illumination the cadmium selenide cell 4 is dominant in producing the signal voltages.

Since the structure and mode of operation of the sensory unit, exemplified in FIG. 4 is very important part of the invention, it is considered necessary to demonstrate its operation. For this purpose four different levels of illumination are assumed. The approximate re- 40 sistances of the photocells 3 and 4 at each of the assumed levels can be obtained from the chart in FIG. 1. The other values such as the resistances of the resistors 5 and 6 and thevoltages of the two sources is given in FIG. 4 of the drawings.

To show the comparisons in values a table, as derived from calculations, is herein provided. The light levels are shown at the top of the table. The resistances of the photocells are designated as R and R respectively, the total resistance across the circuits fed from the separate sources of voltages is represented by R the currents in these circuits are represented by 1 and I The total current across the output circuit is the sum of the separate currents through the photocell 4. The voltage drops VD VD and VD, are respectively the voltage drops produced by the volt source, the 9 volt that a greater omofi'B'r the voltage drop across the output is produced by photocell 4 as the light level decreases. This is evident from the comparison of the VD AND VD values at the lower light levels. At the higher light levels, the photocell 3 produces a voltage drop of 0.927 as compared with a voltage drop of 0.0040 volts for the photocell 4. In this instance it is clear that the photocell 3 produces the greater portion of the voltage drop across the output circuit. In the middle range of changing light levels both cells operate to share in producing the voltage drop across the output circuit.

In addition, in the lower levels of the illumination when cell 3 ceases to produce any significant portion of the output voltage drop, the cell 4, which has a response in the near infra-red region of the light spectrum will be able to see motion that the human eye cannot detect and will produce the significant portion of the signal voltage. To this extent the range of response of the present sensory unit exceeds that of the human eye.

It has been demonstrated how the circuit of FIG. 4 1' operates to satisfy the adaptive function of the sensory means to changing light levels. A more uniform response over the entire range of changing light levels is obtained in the use of the two cells as connected and supplied with energy, than can be achieved by other connections of the two separate cells. 5 Referring now to FIGS. 7 and 8, there is a fragment of a casing 22 that serves to enclose thepower sources, the processing circuitry and to mount the sensory means.

The sensory means comprises of a spherical lens 20 which is used to view an area or space to be placed under surveilence and to project an image. The casing wall 22 is provided with a circular aperture 21 having a diameter somewhat less than the diameter of the spherical lens. A plate 23 havingan aperture 21 of the same diameter as the casing wall engages the opposite surface of the spherical lens. The plate 23 is secured to the casing by a plurality of bolts 24 spaced about the perimeter of the aperture. The spherical lens is held firmly against the inner side of the casing wall.

A retina for receiving the images projected by the spherical lens 20 is mounted on the plate 23. The mounting means for the retina consists of two annularly shaped plates 27 held in spaced parallel relation to each other by a separator located at the ends of theplates 27. The separators are attached to the plates 27, forming a unitary structure therewith. The mounting means is attached to the plate 23 by volts 26 passing through .apertures in the plate 23 and in the separators.

The inner arcuate edges of the plates 27 fit snugly against the surface of the spherical lens and the diametrical dimension of the plates 27 is such as to locate their 3 50 1,000 ft cand. R Smeg. Kilo. l0 Kilo. l Kilo ohms m 7.5 Kilo. 1 Kilo. .5 Kilo. .1 Kilo. ohms R =R,,. +R,+R 5,007,850 101,350 10.850 1,450 ohms R,,,=R +R,,,+R,, 1,007,850 1,001,350 1,000,850 1,000,450 ohms l =E lR .0000005 .000029 .000276 .00206 amps l =E,/R, .00000892 .000008987 .00000992 .000008996 amps VD l;,(R, +R .000392 .03915 2346 .0927 volts VD =I,,(R, +R,,) .0700 .0121 0072 .0040 volts VD,=VD +VD., .0701 .0512 2418 .931 volts source ani irlaiafibrin aeross the output circuit.

- From the above table of values, it can be readily seen outerarcuateedges at thefocal length of the spherical lens.

The'retina is attached to the other arcuatc edges of the plates 27 and is supported thereby between the plates 27. The retina in the illustrated example of the apparatus consists of five sensory units, each containing a pair of cells 3 and 4 electrically connected in series. More than five units may be used if desired and the width of the retina may also be made wider to cover a greater area of the spherical surface of the lens. The cells 3 and 4 arranged parallel to-each other and are spaced from each other just sufficient enough to prevent short circuits. The sensory units, on the other hand, are spaced along the outer edges of the plates 27 and the retina so formed extends over about 30 percent of the circumference of the lens.

The spacing of the sensory units in the circumferential distance about the spherical lens and the orientation of the cells relativeto the vector of motion of the images across their sensitive surfaces is an important consideration in the structure of the sensory means.

For example, in devices of the character of the invention, there are many causes of false alarms, that tend to' render such devices unreliable. It is therefore always desirable in every such deviceto provide a signal with distinguishable characteristics that will enable the real signals to be separated from the false signals. The structure of the sensory means can be utilized to produce such characteristics that will enable the real signal to be separated from the false signals in the processing thereof.

In the present apparatus it is motion of an object or person that is to be detected. The lens projects an image of the object or person on the retina and as the object or person moves in the field of view of thelens the image traverses the retina. There are upper limits and lower limits of speeds of motion which can be expected from the object or person whose motion it is to detect. Other motions, as for example those caused by traveling light patterns caused by passing vehicles, would have other speeds of motion, more often than not, to be outside the speed range of the object or person whose motion is to be detected.

Thespacing of the cells in the equatorial plane can be made such asto produce a frequency of pulsations to the signal that results, which would be within a certain range of frequencies. Other motions would be the cause of the production of signals having a different frequency from that of the real signal. Thus by importingacharacteristic that depends on the rate of motion of the image in traverse 6f albinism the retina [fie real signal can be distinguished and separated from the false signals. To demonstrate reference is made to FIG. 9, wherein the cells arranged in a horizontal line and the traverse of the image is in a horizontal direction. In this instance the image of the movable object in a field of view is much larger than the sensitive area of the cells 3 and 4. As the image moves along the line of travel from one units in the direction of such motion. The range of variations of speed of motion of the image determines the range of frequency variations. The spacing of the units determine the average frequency of the signal due to the motion of the image. The above example pertains to a condition where the field of view is close to the detecting apparatus.

When the field of view of the area under surveilence is at a greater distance from the lens, the image of the movable object produced on the retina will be much smaller and the range of movement of the image will be lessened. In this instance, it is conceivable that the image would be restricted in its extent of movement to the distance between cells 3 and 4. The configuration of the sensitive surface on the cells then becomes a factor in controlling the frequency of the output signal.

,The sensitivematerial of the cells is depositedin a serpentine configuration on the insulating base. In FIG. 9 three example of orientation of the cells are disclosed, namely that of 55 in which the fewer portions of the configuration would be traversed by the image; that of S6 in which a greater number of portions of the configper cell or a number of pulses equal to the number of cells traversed. In the second example 56 the image would traverse the maximum number of sensitive portions of the cell and the frequency of the signal would be at a higher average value. In the third example, that shown'at 57, the configuration would be at an angle to the vector of motion greater than in the first example and less than in the second example and the average frequency of the signal would be between the frequencies of the signals produced in the first two examples. Thus it can be seen, that spacing of the sensory units and the orientation of the cells of the sensory units can be used to introduce a distinctive frequency characteristic to the real signal. i

in the structure of the retina the spacing and the orientation of the cells is madesuch that the average frequency of the realsignals will be within a range acceptable by the processing circuitry, which is tailored to reject signals having frequencies outside the acceptable range. The separation of real signals from-false signals are thus initially made on the basis of their frequency. That is, the real signals will have a very low frequency, whereas, false signals will in most instances have a much higher frequency.

FIGS. 5A and'SB disclose the circuitry of the sensory means and of the processing means, wherein, the real signals are amplified; separated from false signals having a different average frequency than the acceptable frequency; wherein the signal is converted to direct current pulses of uniform amplitude and duration; wherein the pulses are counted or stored fromwhich a triggering pulse is generated to set off the alarm, and; wherein there are several different characteristics to the alarm that can be produced.

FIG. 5A discloses an array of three'sensory'units. There are actually five such units in the inventive example, the smaller number being illustrated tosimplify the disclosure. Each sensory unit comprises respectively, a cadmium sulphide cell P, and a cadmium selenide cell P connected in series with a 330 ohm current limiting resistor R Each series circuit is connected across a low voltage source 3,. A portion of each sensory unit is also fed energy from a higher voltage source B which is connected through a l megohm resistor R,, through the selenide cell P and the current limiting resistor R Each of the sensory units is connected from a point between cells P, and P to and through a capacitor to a terminal of a switch 8,. The right and left sensory units, as seen in FIG. 5A are respectively connected through capacitors C, and C to the terminal t, of the switch 8,. The middle sensory unit of the three illustrated is connected through capacitor C to the terminal t, of the switch 8,. The switch is arranged to connect and disconnect the right and left sensory units to and from the output circuit. The middle sensory unit remains at all times connected to the output circuit. The switch thus functions to control the effective size of the retina of the sensory means.

An ac voltage is produced across the capacitors C,, C, and C This voltage is connected through resistors R and R., to the base of transistor O, and to ground through the capacitors C, and C The resistors R and R and capacitors C C function as a filter network, passing the signals having the ac voltages with the acceptable frequencies to the base of the transistor Q, and to by-pass signals outside the acceptable frequency range to ground. This provides for the elimination of some of the causes of false alarms as for example those caused by flashing lights, signs, and fluorescent lamps and the like.

Transistor Q, has its collector connected to a source of voltage, herein represented by buss 8, and its emitter connected to the base of transistor Q The collector of transistor O2 is connected through resistor R to buss 8 and the emitter through resistor R, to grounded buss 10. The output of transistor 0,, is coupled from its collector to the base of transistor Q Transistor Q, has its collector connected through resistor R to buss 8. The collector is also connected through capacitor C to the base of transistor Q and through resistor R, to the emitter of transistor Q The emitter of transistor O is connected through resistor R to the buss 10, through resistor R to the base of transistor Q, and through the circuit containing capacitor C resistor R,, and switch S to the buss l0. Resistors R ,R,,,R-,,R',, R serve as bias resistors for the amplifier. The resistor R,,, serves as a feedback resistor fixing the gain of the amplifier. This gain can be modified by the operation of the switch 8,, which when closed throws the by-pass circuit, containin g capacitoF O andies istor R" in shunt with resistor R9. This raises the gain of the amplifier over that which is realized when the switch is open. When the switch S2 is open the gain of the transistor Q, is determined by the ratio of the resistances of resistors R8 and R9.

Transistor Q, is coupled from its collector through capacitor C and resistor R to the base of transistor 0,, which has its collector connected through resistor R to the buss 8 and its emitter connected to grounded buss 10. The collector of transistor 0., is also connected back through biasing resistor R and a feedback capacitor C to the base of transistor Q Transistors 0,, Q Q 0., form the analogue portion of the linear amplifier and they provide a high impedance input to the output of the photosenor array used in the sensory means.

Transistor Q, has its collector connected through resistor R,, to the base of transistor Q which in turn has its collector connected to buss 8 through resistor R, and its emitter connected to the buss 10. The collector of transistor Q, is also connected to the terminal 1,, of the NOR gate 6,, composed of two pairs of field effect transistors termed CMOS or complementary metal oxide silicon transistors, which have a low noise factor and low power consumption.

The gate G, has a terminal t,,, coupled to the buss 8, a terminal t,, connected to ground, an input terminal t, and an output terminal t,,. The terminal t, is coupled through capacitor C to the base of transistor 0,, whose collector is connected to buss 8 through resistor R, and whose emitter is connected directly to the buss 10. A biasing resistor R connects the base of transistor Q, to buss 8. The collector of the transistor 0,, is connected through a diode D, and capacitor C,, to buss 10. A bleed path is provided to ground through resistor R,,,, which connects to ground through the base-emitter junction of the transistor 0,. The voltage of the capacitor C is applied not only to the base of the transistor 0,, but also to the terminal I, of the NOR gate 6,.

In operation, theNOR gate G, functions as an'acceptance gate. It limits the passage of pulses to those of a frequency that is below a predetermined value. For example, the terminal t, of the gate G, is' normally at ground potential, that is, when the transistor 0, is rendered conductive, there is a voltage drop across the resistor R and terminal t, is connected to ground through the transistor Q When a negative pulse is applied to the base of transistor 0,, it ceases to conduct while the pulse persists. This produces a decrease in the voltage drop across the resistor R,,; and a positive going pulse on the terminal t, of NOR gate 6,. This in turn produces a negative going pulse at terminal t which when applied through capacitor C, to the base of transistor 0,, decreases the voltage drop across the resistor R to produce a positive going pulse on the capacitor C This causes the capacitor to charge through the diode D,. The diode D, operates to prevent the discharge of the capacitor C, back through the transistor Q The period that the capacitor C remains charged is determined by the resistance in the bleed circuit that includes the resistor R,,,.

terminal t,, of the NOR gate' G, has a plus voltage applied thereto. While this voltage persists, changes in voltage of terminal t will not cause a change in voltage at terminal t, After the capacitor C,, becomes discharged then any pulse delivered to the base of transistor Q, will activate the gate G, and the capacitor will -be recharged. Thus, after each pulse there is a period The gate G and the transistor Q also function as a unitizer, to produce pulses having a uniform amplitude and duration. This is essential in the counting of pulses in the capacitor C The gate G provides at its terminal r pulses of uniform amplitude but not of uniform duration. The capacitor C and resistor R provides the time function to control the duration of the pulses, produced at the collector of transistor Q,,. When the negative pulse from the terminal is applied to the capacitor C and through it to the base of the transistor Q the capacitor C is discharged through the base emitter junction ofthe transistor When the capacitor C becomes sufficiently discharged transistor Q ceases to conduct and the duration of the pulse starts. During the period of non-conductivity of transistor Q, the capacitor C is recharged through the resistor R when the capacitor C becomes'sufficiently recharged the transistor Q again starts to conduct thus ending the duration of the pulse. In this manner the-pulses at the collector become unitized. This assures equal charges being applied to the capacitor C through the diode D for each pulse at collector of Q T l ie esnaarbr raisins; d is cassettes assign diode D resistor R to one terminal of a capacitor C the other terminal of which is connected through a pair of switches S S to the grounded buss 10. This circuit is the main memory. It is provided to receive the unitary or uniform pulses from the collector of transistor Q until there are sufficient number to charge the capacitor C to a voltage adequate to activate an alarm system. The capacitor C and switches S S, are shunted by a bleed resistor R This imposes arequirement, that not only must there be a predetermined number of pulses to initiate the triggering of the alarm system, but also, that the number of pulses occur within a predetermined time interval. In other words, the charge voltage on the capacitor C is dependent on the number and rate of pulses received by it. Once the triggering function is completed, the capacitor C is dis-' charged as will appear as the disclosure proceeds.

The capacitor is connected through resistor R fto the base of transistor Q (FIG. B), which has its collector connected through resistor R to the buss 8 and its emitter connected to the grounded buss 10. A gate G having terminals t and has its terminal n connected to the collector of transistor Q The terminalm of gate ti islconnected throng h re sistor R to the base of transistor Q which has its col- 5 lector connected to buss 8 and its emitter connected to the base of transistor Q16, whose emitter is connected to grounded buss 10. The collector of transistor Q is connected through a coil SC to the buss8. Coil SC operates a relay that energizes a remotely located alarm A]. Q

When there is sufficient charge on m'e'capaiwicgg the transistor Q is rendered conductive. When transistor Q is conductive there is a voltage drop across resistor R that reduces the voltage on terminal i of gate G to ground potential. When terminal 2 goes to ground, terminal t 1 goes positive, rendering the transistors Q and Q conductive, to energize the relay coil SC and sound the alarm A,. When transistor Q10 becomes conductive it is desired that the capacitor C be completely discharged, so that its counting function can always start from the same level after the alarm has been silenced.

5 G is activated, a positive potential from terminal i is applied to the base of transistor 0,, to completely discharge memory capacitor C With the apparatus thus far disclosed, the alarm A, will be sounded for a'brief period determined by the 10 time lag of the circuit and willremain off until the capacitor C13 is recharged up to the voltage necessary to again initiate the energization of the alarm system. It is desired at times to have the alarm continue to sound until a reset operation is made either manually or auto- .l5 matically. For this purpose, an automatic latch circuit is provided.

The latch circuit comprises a diode D switch S and resistor R connected between the terminal t and the base of transistor Q10. When switch S is open, the

20 alarm would be sounded after each recharging of the capacitor C When switch S is closed, and when there is a positive pulse or voltage on terminal t it isapplied to the base of transistor Q to maintain it conductive after the capacitor C is discharged. Continual conductivity of the transistor Q maintains the terminal at ground potential and the gate in the latched mode.

it is sometimes desirable to silence the alarm A after a predetermined time interval after the initiation thereof if there is no continued intrusion. lt sould be noted that while the alarm is activated, the capacitor C is shunted by the transistor Q and cannot be recharged. During this period the intrusion may have ceased. However for there to be an indication as to the cessation of the intrusion or its continuation, the alarm needs to be shut off so that the capacitor. c can be recharged. For this purpose, there is provided an automatic reset circuit. This circuit comprises a capacitor C and resistor R connectedbetween the base of transistorQ and the grounded buss 10. The capacitor C18 is shunted by switch S8, which when closed, ren ders the reset circuit inoperative. The reset circuit further includes a resistor R connected from a point between resistor R38 and capacitor C to the base, of transistor Q Transistor Q11 has its collector-emitter circuit connected between the base of transistor-Q10 and the grounded buss'10. Thus after a period of time determined by the constant of the circuit containing the resistor R and capacitor C15, when the voltage on the capacitor C18 reaches a level sufficient to energize the transistor On it grounds the base of transistor Q 0, which rendersv transistor Q10 non-conductive and 5 causes the unlatching operation to be effected. Thus,

or not the intrusion continues or not.

Once the reset or unlatching operation is completed, it is essential that the capacitor C be quickly discharged. The resistor R would impose a time period on the discharge. To accelerate the discharge of the capacitor C a circuit having a lower resistanceis provided by the diode D and resistor R from the capacitor C to the terminal t Thus while a positive voltage appears on terminal I the diode D is reverse biased and the circuit is non-conductive. When terminal i goes to ground, the diode D is forwardly biased by the voltage on capacitor C and it discharges through the circuit to terminal Thus when again the alarm A, is sounded, the capacitor is conditioned to receive its charge and the charge time is always the same, because the charging starts with the capacitor C discharged.

As is seen from the structure thus far disclosed, the reset operation takes place after a predetermined time interval determined by the RC constant of the resistor R38 and capacitor C18. If it is dfiEdtdFoTtihfithe sounding of thegarm while the intrusion of the area under surveillance continues, it would be necessary to interrupt the function of the automatic reset circuit.

A circuit is provided to perform what I term a refresh operation. In effect, the operation is to extract charge from the capacitor C during its charging period, so that the reset function is delayed while pulses are being transmitted from the transistor Q indicative of continued motion in the area under survailance.

For this purpose there is a pair of transistors-Q Q for shunting the capacitor C Capacitor Q has itsbase electrode energized through resistor R from the base of transistor Q Its emitter is connected to grounded buss l and its collector is connected to the emitter of transistor Q The collector of transistor O is connected to the reset timing circuit between resister R and capacitor C The base of transistor Q is connected through resistor R to the collector of transistor Q (FIG. A).

Transistor Q is non-conductive unless and until the alarm circuit to the base of transistor Q is energized. When this circuit is energized the alarm A, will be sounded and capacitor C would charge through resistor R At the same time, the base of transistor Q would be at a positive potential, to thus enable the transistor Q which will only be conductive if and when transistor Q14 is conductive. Transistor OH is rendered conductive during the period transistor Q1 is enabled, by pulses transmitted from transistor Q through resistor R to its base. When this occurs, transistors Q and 0, establish a shunt around capacitor C to ground and causes it to be discharged during the period of the pulse. Thus, the reset means is said to be refreshed, or the charging period is started over anew at each incidence of a pulse from transistor 0,, upon the base of transistor Q The reset operation is thus delayed while there is motion in the field of view of the sensory means and the alarm is continuous until a predetermined time interval after all motion ceases.

After an alarm has been initiated by an intrusion that is sensed by the sensory means, the capacitor C is discharged by the energization of transistor Q The capacitor C will remain shunted by transistor Q so long as the alarm circuit is energized from terminal t of gate G After the reset time has expired, the shunt provided by transistor 0,, is removed. Then and only then can the memory capacitor C be recharged. As is evident, it requires several pulses from transistor O to raise the charge on the capacitor C to the level to again trigger transistor O This amounts to a temporary loss of sensitivity. That is, during the charging period of capacitor C no re-initiation of the alarm can be had. To eliminate this loss of effectiveness of the apparatus, an anticipatory circuit is provided to provide for continued effectiveness while the capacitor C is being recharged. The function is particularly desirable in instances where an alarm has been sounded and it is surveillance.

The circuit to provide the anticipatory function consists of a charging circuit having diode D a resistor R and a capacitor C connected in series between terminal t of gate G and the grounded buss. l0. Capacitor C is shunted by a switch 8, when closed renders the circuit inoperative. The circuit provides a charging of capacitor C up to the voltage appearing across the circuit and because of the diode D, for the trapping of the charge onthe capacitor C The circuit is connected from a point between resistor R and capacitor C through resistor R to the collector of transistor On. The emitter of transistor Q is connected to the grounded buss 10 and its base is connected through resistor R to the collector of transistor Q, from which unitized pulses are received.

The collector of transistor Q12 is connected through exgected that motion will continue in the area under resistor R and capacitor C to the base of transistor Q For a time interval, determined by the RC constant 'of the circuit including the resistor R and capacitor C there is insufficient voltage appearing at the collector of transistor Q12 to render it capable of operation. It requires but a short interval of time for the capacitor to reach a charge adequate to enable transistor Q12. During the period while the charge is taking place capacitor C is fully discharged. After the reset operation has taken place the transistor Q ceases to conduct. When a new pulse is admitted to the memory capacitor C it is also applied through resistor R to the base of transistor Q which is enabled by the charge on capacitor' C to conduct during the period of the pulse. This causes a positive pulse to be applied to the base of transistor Q whereby, the alarm A is sounded on the first pulse instead of after several pulses later as would be the case if the memory capacitor had to be relied upon to produce the triggering pulse.

Thus, with the switch 8, open, it would require several pulses from transistor Q, to initially trigger an alarm and thereafter, it would be re-triggered by each pulse occuring after the reset function is performed. Thus, once the alarm is sounded, the circuit anticipates that the cause to re-trigger the alarm exists and in effect automatically alters the response of the apparatus from one, which for example requires severalpulses to one requiring but a single pulse, after once the alarm has been sounded.

In addition to provisions for energizing a remotely located alarm, the detecting apparatus has a built in alarm A such as a speaker device. This alarm is activated from the transistor Q at the same time that alarm A is activated.

The circuit includes a pair of gates G and G connected together to form a free running multivibrater. Gate G has a terminal t connected to the collector of transistor Q10 in the same manner as gate G is connected thereto. Terminal t of gate 6,, is connected to terminals t and i of gate G Terminal r of gate G, is connected through resistor R to the base of transistor Qw, which has its collector-emitter circuit in series with resistor R connected between thebusses 8 and 10. A switch S shunts transistor Q19 when it is desired to render the internal alarm A silent. The circuit between resistor R, and transistor 019 is connected to the base of transistor 0 having its emitter connected to the base of transistor Q which in turn has its emitter connected to the buss 10. The collectors of transistors Q Q are connected through the buss 8.

Terminal r of gate (i is connected through capacitor C to the collector of transistor Q Terminals t Z are connected through resistor R and capacitor C to the collector of transistor Q Terminals r, is connected back through capacitor C and resistor R. to terminals i of gate 6., and to terminal of gate G When transistor Q10 becomes conductive, there is a voltage drop across the resistor R that causes a ground potential to be applied to terminal t of Gate G This cases a positive potential to be applied to the terminal t and to terminals r of gate G Gate 6., provides a pulsating voltage at terminal thereof, which when applied to transistor Q and transistors 311,018 produce an audio frequency output from the alarm device A The feed back circuit through capacitor C provides for the control over the frequency the output.

All of the functions, such as the auto-reset, latching, refresh, and anticipate operations are also reflected in the output of the alarm A2. In addition, terminals as of the alarm device A to gate G receives pulses through capacitor from the col-- lector of transistor Q which while the terminal t isat ground potential, will modulate the sound of the alarm A with the reception of the pulses from transistor Q This indicates not only that motion is taking place but also by the frequency of the modulation of the sound from the alarm A the rate of motion and the motion ceases. Thus from thenature of the sound of the alarm A one can judge what is taking place in the field of view of the sensory means.

The apparatus further includes a means that permits the arming thereof to be programed to take place at a predetermined interval of time after it has been programmed. This is particularly important under circumstances where it is desired to place the apparatus'in a position such that it views the avenue of approach to the apparatus, thus preventing anyone to approach the apparatus to shut it off. Unless some delay means is provided, the alarm would be triggered by the one who sets it. up.

The means for delaying the arming of the apparatus includes a source of energy B under. the control of switch S which has two positions, one which connects buss 8 to the source of energy and a position in which the source of energy B is connected to a charging circuit having capacitor C therein. Capacitor C is shunted by a bleed resistor R for slowly discharging the capacitor C when the switch S is disconnected therefrom.

The charging circuit is connected through resistor R to the base of transistor Q which has its emitter connected to the buss 10. The collector of transistor 08 is connected to the base of transistor Q whose emitter is connected to the buss 8 and whose collector is connected through resistor R to a light emitting diode LED which acts as an indicator, to indicate when glowing, that the apparatus is programmed to become armed.

While the switch S is in the left hand position as viewed in FIG. SB, the capacitor C is charged and maintained charged. Buss 8 is at thistime disconnected from the source of energy B therefore, the emitter of 16 transistor Q and the collector of transistor 0,, have no voltage thereon and are non-conductive.

The indicator circuit is connected from a point thereof between transistor 0 and resistor R to the terminal r of gate G also, through-the diode D to the terminal of gate G collector of transistor O and terminal r of gate G The indicator line is also connected-to the base of transistor Q,, from a point between the resistor R- and the light emitting diode .LED While the switch remains in the left had position no potential will be applied to any of the above enumerated terminals.

When the switch S is moved into its right hand position, as viewed in FIG. 5B, the buss 8 becomes energized, the transistors Q and become conductive and the indicator light glows to show that the arming is in progress. The positive potential impressed on terminals t 1,, and I from the indicator line preventsthe operation of the alarm means for the duration of the charge on the capacitor C When the capacitor C becomes discharged, the potentials applied therefrom on the terminals t and r and to the base of transistor O are removed, because the transistor Q and become non-conductive with the discharge of the capacitor C When this occurs, the apparatus will be armed. The light LED will cease to glow indicating that the apparatus is armed.

The functions of the apparatus are illustrated in FIG. 6 of the drawings.

The space or area to be placed under surveilence is focused on the retina of the sensory means 25 by positioning the apparatus in the proper orientation relative to the space or area. The image of the area will form stationary light patterns over the retina which will depend on the ambient light level for intensity. When a person or object in the image moves relative to other objects in the area, the image of the movable object moves-on the sensory units and between the sensory units to cause a change in resistance of the cells of the units. The change in the resistance of the cells causes a change. in the current through them and it is this change that brings .about a pulse in the output of the sensory mean.

As has been mentioned, the ambient light level provides a'static resistance in the cells. This resistance varies from a very high value, in the region of megohms, at low light levels to a comparatively low resistance at high light levels. Because of this, the sensory means has wide changes in the output impedance. The impedance converter 31 operates to match the impedance of the sensory means to the signal processing circuitry.

When the image of the movable object moves across the serpentine sensitive surface of the individual cells and across the retina .as a whole it causes a rapid fluctuation of the resistance, the current and the voltage. The frequency of the fluctuations caused by an intruder fall within a predetermined range of frequencies. Changes in resistance from other causes as for eiiample those caused by a fluorescent light have other frequencies outside the range of frequencies of the signals that are of interest. The input to the signal processing means is tailored to receive signals having the frequencies of the signals of interest and to reject others that have frequencies other than those within the acceptable range. The preamplifier and filter 32 separates the signals on the basis of frequency and amplifies the segregated signals.

From the preamplifier, the signals are fed to what is termed a pulse unitizer and acceptance gate 33.'Each pulse is made up an an alternating current voltage in the preamplifier, with a frequency acceptable to the preamplifier. The number of pulses per second is the pulse frequency. The acceptance gate 33 is designed to accept only those pulses that have a frequency below a predetermined level. The pulses that are admitted, operate to generate pulses having a uniform amplitude and duration, or a uniform energy content. The unitizing of the pulses is essential for the counting function performed in the pulse count memory 34 to which the unitized pulses are fed.

In the pulse count memory 34 the pulses of equal increments charge up the capacitor C, raising the voltage thereon in increments from a zero level to the level of the threshold of switch gate 35. The capacitor C has a bleed rate, therefore, the pulses in storage depend on the number of pulses received and on the rate at which the pulses are received. This characteristic of the memory 34 causes the further segregation of the true signal from the other signals that have escaped segregatron.

The switch gate 35 produces a voltage which controls the sounding of the alarm 37 through the means 36 which supply the operating energy to the alarm.

The switch gate 35 can respond to each and every triggering voltage to produce a short sounding alarm signal or it can respond in such a manner as to initiate the alarm and maintain it sounding until the gate 35 is reset. Switches are provided in the apparatus to select the mode of operation desired. When switch 44 is closed the gate 35 is latched intoits on state. Switch 44 merely represents the function of switch S in the actual structure. The gate 35 remains latched until a reset operation is performed. This can be performed manually as by opening the switch S or automatically after an elapse of a predetermined time interval.

When the gate is turned on a voltage is produced at its output terminal. This voltage is fed to the auto reset means 38 which operates back through the reset inhibit gate 39 to the switch gate 35 to cause the unlatching operation or reset operation to take place. Thus the alarm sounds for a predetermined length of time and then shuts off. and will not again be sounded until the memory again stores the required number of pulses.

The time interval to effect the reset operation may be prolonged if desired in response to continual pulses. For example, should there be an intrusion of the area undersurveillanc fii e alarfii would soundand 66mm? to sound until the reset operation takes place. If during this interval there is movement in the area under sur-' veilence, pulses will continue to be generated. These pulses are fed to the reset inhibit gate 39 to effect a refresh operation. The refresh operation simply stated, is to restart the timing each time a new pulse is received while the timing operation is in process. Thus, while there is motion in the field of view of the lens the reset means will be refreshed and the reset operation will be delayed until the motion has ceased.

When the alarm starts sounding, energy is supplied to the means 40, that performs the anticipate function. As will be recalled, the pulse count memory requires a predetermined number of pulses to be in storage for'the triggering voltage to be raised to the required level. After the triggering operation is performed, the memory 34 is rendered inoperative and any pulses received while the alarm is being sounded are simply not counted or stored in the memory 34. After the reset operation, the memory again starts its counting operation. which is dependent on the amount of motion taking place in the field of view of the lens means. It is desired that after the alarm has been initiated, that for a predetermined period after reset that the alarm respond to each individual pulses thus to eliminate the delay caused by the memory. The pulses fed to the means 40 bypasses the memory 34 and act directly on the switch gate 35 to resound the alarm after each pulse, and in this way the length of time that motion continues can be determined.

The delayed arming means functions as clearly stated herein. It includes a jack means through which a remote control can be plugged into the apparatus to enable the apparatus to be rendered inoperative for a periadrsauirsstfor.autb izes p to enter the area under surveillance.

The purposes, the mode of operation and the structure by which the mode of operation is attained have all been disclosed, that which I consider to be my invention is set forth in the following claims.

I claim:' 1. Apparatus for detecting motion within a predeterspace comprising:

lens means for projecting an image of objects in said space;

retina means for receiving said image and producing alternating current voltage pulses in response to motion of said objects in said image; comprising a plurality of sensory units spaced from each other at the focal length of said lens means, each sensory unit having at least two photosensitive cells, each 3 cell having optimum light level response characteristics that cover a different range of changes in light level, but in which the characteristics overlap to cover the entire range of changes of light level from full sun-light to darkness; means for receiving said alternating current voltage pulses and for amplifying those alternating current voltage pulses having a frequency falling within a predetermined range of frequencies; unitizing means'responsive to said amplified alternating current voltage pulses for producing direct current voltage pulses of uniform amplitude and duration;

storage means for receiving said direct current voltage pulses of uniform amplitude and duration and for developing a triggering voltage;

triggering means responsive to a predetermined level of voltage in said storage means to produce a triggering operation; and

alarm means responsive to said triggering operation for producing an indication that motion of objects in said spacehas been detected.

2. Apparatus as set forth in claim 1 further including;

latch means responsive to the operation of said triggering means to maintain said triggering means in operation to latch said alarm means in its continuous operation mode.

3. Apparatus as set forth in claim 2 further including;

reset means for automatically discontinuing the operation of said triggering means for unlatching said alarm means a predetermined time interval after the latching thereof. 4. Apparatus as set forth in claim 3 further including;

refresh means responsive to the direct current voltage pulses from said unitizing means for prolonging the time interval between the latching of said alarm means and the operation of said reset means.

5. Apparatus as set forth in claim 4 further including;

pulse anticipating means enabled during the latch mode of operation of said alarm means operable in response to each direct current voltage pulse from said unitizing means occuringwithin a predetermined time interval after the unlatching of said alarm means to cause a renewed operation of the alarm means. v 6. Apparatus as set forth in claim 5 further including;

means for programming the arming of said apparatus to occur at a predetermined time interval after being initiated, said means comprising;

a circuit which when energized applies a disabling voltage to said triggering means to prevent said triggering means from operating;

means for energizing said circuit and said apparatus;

a timing means to determine the interval during which said circuit remains energized; and

indicator means in said circuit to indicate when said circuit is energized. 7. Apparatus as set forth in claim 1 further including;

means for selectively varying the effective size of said retina, comprising switch means for rendering certain of the spaced sensory units inoperable.

8. A sensory apparatus for detecting motion of objects in a predetermined space comprising:

a second photosensitive cell having optimum response at the lower levels of illumination; a first resistor having a comparatively low resistance;

a second resistor having a comparatively high resistance;

a first and second source of energy the first having a low voltage and the second having a higher voltage;

a first circuit means for connecting said first and second cells and said first resistor in series with said first source of energy;

a second circuit means for connecting said second resistor, said second cell and said first resistor in series with said second source of energy; whereby the first cell is dominant in producing voltage pulses during high levels of illumination and the second cell is dominamt in producing pulses during low levels of illumination and both cells contribute to produce voltage pulses during medium levels of illumination, whereby voltage pulses of optimum strength are produced over the full .range of changes in illumination level.

9. Apparatus as set forth in claim 8 wherein said second photosensitive cell has a response in the near infrared region of the light spectrum, whereby the range of response of the sensory means is extended beyond the visible light spectrum.

10. A sensory unit comprising a plurality of photosensitive cells, each cell having a different sensitive material and optimum response over different portions of the range of change of illumination from full sun-light to darkness;

a first source of voltage of one value;

a current limiting resistor;

means connecting said cells in series with said source of voltage and said current limiting resistor;

a second source of voltage of higher value than the first of voltage;

a fixed resistor connected in series with said second source of voltage, one of said cells and said current limiting resistor; and

output-means connected across one of said cells and said current limiting resistor; whereby voltage pulses of optimum strength will be produced for all levels of illumination. 

1. Apparatus for detecting motion within a predeterspace comprising: lens means for projecting an image of objects in said space; retina means for receiving said image and producing alternating current voltage pulses in response to motion of said objects in said image; comprising a plurality of sensory units spaced from each other at the focal length of said lens means, each sensory unit having at least two photosensitive cells, each cell having optimum light level response characteristics that cover a different range of changes in light level, but in which the characteristics overlap to cover the entire range of changes of light level from full sun-light to darkness; means for receiving said alternating current voltage pulses and for amplifying those alternating current voltage pulses having a frequency falling within a predetermined range of frequencies; unitizing means responsive to said amplified alternating current voltage pulses for producing direct current voltage pulses of uniform amplitude and duration; storage means for receiving said direct current voltage pulses of uniform amplitude and duration and for developing a triggering voltage; triggering means responsive to a predetermined level of voltage in said storage means to produce a triggering operation; and alarm means responsive to said triggering operation for producing an indication that motion of objects in said space has been detected.
 2. Apparatus as set forth in claim 1 further including; latch means responsive to the operation of said triggering means to maintain said triggering means in operation to latch said alarm means in its continuous operation mode.
 3. Apparatus as set forth in claim 2 further including; reset means for automatically discontinuing the operation of said triggering means for unlatching said alarm means a predetermined time interval after the latching thereof.
 4. Apparatus as set forth in claim 3 further including; refresh means responsive to the direct current voltage pulses from said unitizing means for prolonging the time interval between the latching of said alarm means and the operation of said reset means.
 5. Apparatus as set forth in claim 4 further including; pulse anticipating means enabled during the latch mode of operation of said alarm means operable in response to each direct current voltage pulse from said unitizing means occuring within a predetermined time interval after the unlatching of said alarm means to cause a renewed operation of the alarm means.
 6. Apparatus as set forth in claim 5 further including; means for programming the arming of said apparatus to occur at a predetermined time interval after being initiated, said means comprising; a circuit which when energized applies a disabling voltage to said triggering means to prevent said triggering means from operating; means for energizing said circuit and said apparatus; a timing means to determine the interval during which said circuit remains energized; and indicator means in said circuit to indicate when said circuit is energized.
 7. Apparatus as set forth in claim 1 further including; means for selectively varying the effective size of said retina, comprising switch means for rendering certain of the spaced sensory units inoperable.
 8. A sensory apparatus for detecting motion of objects in a predetermined space comprising: lens means for viewing said space and for forming images of the objects in said space; retina means for receiving said images caused by motion of objects in said space comprising; a plurality of sensory units spaced from each other at the focal length of said lens means, each sensory unit comprising; a first photosensitive cell having an optimum response at the higher levels of illumination; a second photosensitive cell having optimum response at the lower levels of illumination; a first resistor having a comparatively low resistance; a second resistor having a comparatively high resistance; a first and second source of energy the first having a low voltage and the second having a higher voltage; a first circuit means for connecting said first and second cells and said first resistor in series with said first source of energy; a second circuit means for connecting said second resistor, said second cell and said first resistor in series with said second source of energy; whereby the first cell is dominant in producing voltage pulses during high levels of illumination and the second cell is dominamt in producing pulses during low levels of illumination and both cells contribute to produce voltage pulses during medium levels of illumination, whereby voltage pulses of optimum strength are produced over the full range of changes in illumination level.
 9. Apparatus as set forth in claim 8 wherein said second photosensitive cell has a response in the near infra-red region of the light spectrum, whereby the range of respOnse of the sensory means is extended beyond the visible light spectrum.
 10. A sensory unit comprising a plurality of photosensitive cells, each cell having a different sensitive material and optimum response over different portions of the range of change of illumination from full sun-light to darkness; a first source of voltage of one value; a current limiting resistor; means connecting said cells in series with said source of voltage and said current limiting resistor; a second source of voltage of higher value than the first of voltage; a fixed resistor connected in series with said second source of voltage, one of said cells and said current limiting resistor; and output means connected across one of said cells and said current limiting resistor; whereby voltage pulses of optimum strength will be produced for all levels of illumination. 